JPH0690528A - Static type reactive power generator - Google Patents

Abstract

PURPOSE:To improve a response, and to suppress an overshoot by compensating for a waste time that arises during a period for preventing the short-circuit of a gate turn-off thyristor when a leading phase and a lagging phase of a reactive current are mutually switched. CONSTITUTION:A reactive current reference signal IQ* is introduced into a phase-difference reference compensating circuit 20. When a reactive power generated by a static type reactive power generator is switched to a leading phase or a lagging phase, a phasedifference reference signal DELTAphi is compensated. An output voltage of a capacitor 5 for use as a d.c. voltage supply is controlled in such a way that it is switched to a leading phase or a lagging phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static reactive power generator for adjusting reactive power of a grid.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a control circuit of a conventional static reactive power generator. In the figure, 1 is a system power supply, 2 is a reactor, 3 is a multiple transformer connected to the system power supply 1 via this reactor, 4 is a single-phase inverter connected in multiple stages to this multiple transformer, and 5 is this single-phase inverter. For DC voltage source for supplying DC voltage to the system, 6 for system voltage detection PT, 7 for system current detection CT, 8 for system voltage detection PT6, and system voltage detected by system current detection CT7, and system Introduce current, P
A sensor for detecting the WM phase reference φ ₀ , the reactive current I _Q and the effective voltage V _P , 9 a sensor for detecting the DC voltage output from the DC voltage source capacitor 5, and 10 a pulse for controlling the gate of the single-phase inverter 4. A width modulation (hereinafter, pulse width modulation is referred to as PWM) circuit, 11 introduces a DC voltage reference signal V _d ^* and a DC feedback signal V _d detected by the sensor 9 to generate a system voltage so that the deviation becomes zero. A phase difference reference signal Δφ with the output voltage of the static reactive power generator is calculated, and the above P
A DC voltage controller (composed of a proportional-integral element) for outputting to the WM circuit, 12 is a conduction angle reference of the inverter device 4 based on the deviation between the reactive current _IQ detected by the sensor 8 and the reactive current reference signal _IQ ^*. A reactive current controller (composed of proportional-plus-integral elements) that controls the reactive current by deriving the signal θ ^* and supplying it to the PWM circuit, 13 is the effective voltage V _P detected by the sensor 8 and the system effective voltage reference V A system voltage controller (composed of proportional-plus-integral elements) that introduces _P ^* and supplies a reactive current reference signal _IQ ^* to the reactive current controller 12 based on these deviations, 14 is from each of the controllers 11 to 13 Control circuit part composed, 1
Reference numeral 5 indicates an adder.

FIG. 6 shows an example of a constituent circuit of the single-phase inverter 4 shown in FIG. 5, 31 is a gate turn-off thyristor, 32 is a diode, 33 is a transformer, and 34 is an AC power source. 7 (a), (b), and (c) show the output voltage waveform V _I and the output current waveform i when the single-phase inverter of FIG. 6 outputs a lag current, and the turn-on or turn-off of the gate turn-off thyristor. The timing chart of a period and the vector diagram of voltage current are shown. 8 (a), (b), (c)
6 shows the output voltage waveform V _I and the output current waveform i when the single-phase inverter of FIG. 6 outputs a phase-advancing current, the timing chart of the ON or OFF period of the gate turn-off thyristor, and the voltage-current vector diagram. . In FIGS. 7 and 8, Td is a short circuit prevention time (hereinafter referred to as Td) in which a gate-on signal is not simultaneously applied to prevent a short circuit between the gate turn-off thyristors T _A and T _B or T _C and T _D in FIG.
(d).

Next, the operation of the above configuration will be described. First, the basic principle of the static reactive power generator will be described. When the magnitude, frequency, and phase of the output voltage of the static reactive power generator (the output voltage of each inverter 4 is combined by the multiple transformer 3) are synchronized with the grid voltage, the static reactive power generator flows from the grid. However, if the output voltage V _I of the static reactive power generator is controlled to be higher than the system voltage V _S (V _I > V _S ) as shown in FIG. 8, the static reactive power generator advances from the static reactive power generator. When the phase current i flows out and conversely the output voltage V _I of the static reactive power generator is lower than the system voltage V _S (V _I <V _S ) as shown in FIG. 7, the static reactive power generator delays the phase current i. i flows out.

In order to control the reactive power, it is sufficient to control the output voltage of the static reactive power generator, but in general,
To this end, the flow angle θ of the single-phase inverter 4 is kept constant and the DC voltage of the DC voltage source capacitor 5 is variably adjusted,
A PAM method for controlling the output voltage of the single-phase inverter 4,
There is a PWM method in which the DC voltage of the DC voltage source capacitor 5 is kept constant and the conduction angle θ of the single-phase inverter 4 is variably adjusted to control the inverter output voltage value, but FIG. 5 shows the latter PWM method. is there. In addition, the DC voltage source capacitor 5
Is controlled by the phase difference Δφ between the system voltage and the output voltage of the static reactive power generator, and the output voltage of the static reactive power generator is controlled by the conduction angle θ of the single-phase inverter 4. Here, the inverter output voltage is represented by the following equation.

V _0I = 4 / (√2 · π) · Ed · sin (θ / 2) (1) θ: Inverter _conduction angle Ed: DC voltage V _0I : Effective value of fundamental wave of inverter output voltage

Further, the DC voltage of the DC voltage source capacitor 5 is controlled by the phase difference reference signal Δφ calculated by the DC voltage controller 11 from the constant DC voltage reference signal V _d ^* and the DC voltage feedback signal V _d. . That is, the phase difference Δφ
Since the output voltage of the static reactive power generator is delayed from the system voltage, the active power supplied from the system becomes larger than the losses of the single-phase inverter 4 and the multiple transformer 3, and the DC voltage source capacitor 5 DC voltage rises. At this time, if the inverter conduction angle θ does not change, the static reactive power generator supplies the advanced reactive power by increasing the DC voltage of the DC voltage source capacitor 5. On the contrary, by setting the phase difference Δφ to be the lead phase of the output voltage of the static reactive power generator rather than the system voltage, the loss of the single-phase inverter 4 and the multiple transformer 3 is smaller than the active power supplied from the system. It becomes large and the DC voltage of the DC voltage source capacitor 5 drops. At this time, if the inverter conduction angle does not change, the static reactive power generation device supplies the delayed reactive power because the DC voltage of the DC voltage source capacitor 5 drops.

Next, referring to FIGS. 6, 7 and 8, the leading phase current and the lagging phase current output from the inverter will be described. In order to output the lagging phase current, the inverter output voltage is V _S >.
The inverter conduction angle θ is controlled so as to be V _I, and the inverter conduction angle θ is controlled so that the inverter output voltage is V _S <V _I in order to output the advanced current. At this time, the on / off timing of the gate turn-off thyristor is set to T in order to prevent the above-mentioned short circuit between the phase advance and the phase delay mutual transition.
The phase is shifted between d. Next, to describe the system voltage control, the system voltage controller 13 calculates the reactive current reference signal _IQ ^* based on the supplied system voltage reference signal V _P ^* and system voltage feedback signal V _P. This reactive current reference signal _IQ ^* controls the reactive power generated by the static reactive power generator.

That is, based on the reactive current reference signal I _Q ^* and the reactive current feedback signal I _Q , the reactive current controller 12
The calculated conduction angle reference signal of the single-phase inverter 4 that eliminate the deviation between theta ^*, the conduction angle reference signal theta ^* is PW
It is given to the M circuit 10, the gate pulse of each single-phase inverter 4 is determined by the PWM circuit 10, and given to each single-phase inverter 4. The multiple transformer 3 combines the output voltages of the single-phase inverter 4 and generates the output voltage V _I of the static reactive power generator. Reactive power is generated via the reactor 2 due to the generated difference voltage between the output voltage V _{I of} the static reactive power generator and the system voltage V _S.

[0010]

Since the conventional static reactive power generator is configured as described above, it is possible to change the reactive power to be output from the advanced phase to the delayed phase.
Since the conduction angle control by the reactive current controller is interrupted during Td, there is a dead time due to Td at the mutual switching point between the advanced phase and the delayed phase, which causes an increase in the overshoot amount of the reactive power, and the reactive power control response. Can't raise. Further, if the response of the reactive power control by the DC voltage controller is increased in order to reduce the influence of Td, the resonance of the system constant and the DC capacitor becomes unstable, and the response of the DC voltage controller cannot be increased. was there.

The present invention has been made in order to solve the above problems, and it transiently uses the reactive current reference signal at the switching point between the advanced phase and the delayed phase of the reactive power to transiently provide the phase difference reference signal. It is an object of the present invention to obtain a static reactive power generation device capable of stable reactive power control by compensating for dead time due to Td by compensating for.

[0012]

SUMMARY OF THE INVENTION A reactive power generator according to the present invention introduces a reactive current reference signal and compensates for a phase difference reference signal output from a DC voltage controller at the time of phase advance or lag phase mutual switching. It is provided with a circuit.

[0013]

The static reactive power generator according to the present invention comprises:
When the reactive power is switched between the advanced phase and the delayed phase, the output voltage of the DC voltage source capacitor is controlled in the advanced or delayed direction by compensating for the phase difference reference signal of the DC voltage controller. Time is compensated and stable reactive power control is performed.

[0014]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a static reactive power generator according to this embodiment. In the figure, the same reference numerals as those in FIG. 5 denote the same parts, 16 is a circuit simulating the reactive current feedback signal with respect to the reactive current reference signal _IQ ^* , which is composed of proportional and temporary delay elements, and 17 is the above A limiter circuit that limits the simulated reactive current feedback signal,
The output of the proportional temporary delay circuit 16 is limited to the control amount corresponding to Td. The difference between the output signal of the limiter circuit 17 and the output signal of the DC voltage controller 11 is calculated, and the PWM circuit 1
The phase reference signal Δφ is output to 0. Reference numeral 20 is the phase difference reference compensation circuit configured as described above.

Next, the operation will be described. In the configuration shown in FIG. 1, the part of the prior art described with reference to FIG. 5 operates in the same manner, so description thereof will be omitted. The operation of the part of the phase difference reference compensation circuit 20 according to the present embodiment will be described with reference to FIG. This will be described with reference to the transient characteristics of the reactive current response shown. First,
A conventional technique in the case where there is no phase difference reference compensation circuit 20 shown by the solid line in FIG. 2 will be described. Consider a case where the reactive current reference signal _IQ ^* changes largely in a stepwise manner from negative (late phase) to positive (lead phase). The reactive current feedback signal I _Q will no longer vary once around zero, the subsequent DC voltage controller 11 along with the DC voltage feedback signal V _d varies is varied more between Td retardation reference signal [Delta] [phi, reactive current feedback The signal I _Q operates again so as to follow the reactive current reference signal I _Q ^* . In addition, the reactive current I _Q because there is a dead time due to the Td overshoots.

Next, when the phase difference reference compensation circuit 20 is inserted at this time, it becomes as shown by the dotted line in FIG. 2, and the proportional temporary delay circuit 16 receives the reactive current reference signal _IQ ^* as an input and simulates invalidation. issues a current feedback signal I _Qm, the limiter circuit 17 limits the amount of Td corresponding to the I _Qm, so to compensate for the phase difference reference signal, the dead time is reduced, reactive current feedback signal I _Q is rising It becomes faster and does not overshoot.

Example 2. In the first embodiment, the case where the phase difference reference signal is compensated by the phase difference reference compensating circuit 20 has been described, but in the second embodiment, the integrator 18 simulating the DC power supply capacitor as shown in FIG. A proportional gain 19 is provided, and a phase difference reference compensation circuit 21 configured to feed back the phase difference reference compensation signal to the input side of the DC voltage controller 11 is provided. In FIG. 3, the same parts as those of the first embodiment are omitted because they are the same in operation, and the addition of the polarity inversion signal of the output signal of the limiter circuit 17 and the output signal of the DC voltage controller 11 is input to the integrator 18 and simulated DC The voltage signal is calculated, the simulated DC voltage feedback signal and the DC voltage feedback signal are subtracted, the difference signal is multiplied by K by the proportional gain 19, and the phase difference compensation signal is added to the input of the DC voltage controller 11. There is. Example 2 shown in FIG. 3 in FIG.
The transient operation of will be described. The simulated DC voltage feedback signal V _dm starts to change faster than the DC voltage feedback signal V _d , and a difference occurs between the two. The difference signal is proportionally multiplied by the circuit 19 to calculate the phase difference reference compensation signal, and the DC voltage controller 11
When fed back to, the DC voltage controller 11 calculates the phase difference reference so as to make the phase difference reference compensation signal zero, and therefore the operation shown by the dotted line in FIG. 4 becomes the same operation as that of the first embodiment.

[0018]

As described above, according to the present invention, the reactive current reference signal is input, the phase difference reference compensation signal is calculated, the phase reference signal is compensated, and the dead time due to Td is compensated. Since it is configured as described above, there is an effect that the control response of the reactive power is improved and a stable static reactive power generation device can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a static reactive power generator showing a first embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating an operation of transient characteristics by the phase difference reference compensation circuit according to the first exemplary embodiment.

FIG. 3 is a block diagram of a static reactive power generator showing a second embodiment of the present invention.

FIG. 4 is a waveform diagram illustrating an operation of transient characteristics by the phase difference reference compensation circuit according to the second exemplary embodiment.

FIG. 5 is a block diagram showing a conventional static reactive voltage generator.

FIG. 6 is a circuit diagram showing a single-phase inverter circuit.

FIG. 7 is a diagram showing an output voltage and an output current, a gate turn-off thyristor on / off timing, and a voltage / current vector when a lagging phase current is output in a single-phase inverter circuit.

FIG. 8 is a diagram showing an output voltage and an output current when a phase-advancing current is output in the single-phase inverter circuit, an ON / OFF timing of a gate turn-off thyristor, and a voltage-current vector.

[Explanation of symbols]

 1 System Power Supply 2 Reactor 3 Multiple Transformer 4 Single Phase Inverter 5 DC Voltage Source Capacitor 6 System Voltage Detection PT 7 System Current Detection CT 8 Sensor 9 Sensor 10 PWM Circuit 11 DC Voltage Controller 12 Reactive Current Controller 13 System Voltage Controller 14 Control circuit 16 Proportional temporary delay circuit 17 Limiter circuit 18 Integrator 19 Proportional gain circuit 20, 21 Phase difference reference compensation circuit

Claims (1)

[Claims] 1. An inverter device connected to a power system via a transformer, a DC voltage source capacitor for supplying a DC voltage to the inverter device, a system voltage, and a system current are introduced, and a system reactive current and an effective voltage are introduced. , A first sensor for detecting a synchronization phase reference signal, a second sensor for detecting an output voltage of the DC voltage source capacitor, and a first sensor
Of the system active voltage and system active voltage reference detected by the sensor, and derives the reactive current reference signal based on these deviations, the reactive current reference signal derived by this system voltage controller and the first A reactive current controller that introduces a system reactive current detected by a sensor and derives a conduction angle reference signal of the inverter device based on these deviations, an output voltage of a DC voltage source capacitor detected by the second sensor, and A DC voltage controller for deriving a phase difference reference signal for controlling the output voltage of the DC voltage source capacitor based on a deviation from a DC voltage reference signal given in advance, the DC voltage controller, the reactive current controller, and the first The phase difference reference signal, conduction angle reference signal, and synchronization phase reference signal obtained from the sensor Pulse width modulation control circuit for controlling the switching of the power supply device, introducing the reactive current reference signal derived from the system voltage controller, and compensating for the phase reference signal of the DC voltage controller at the time of phase advance or lag phase mutual switching. A static reactive power generation device comprising a compensation circuit for controlling the output voltage of the DC voltage source capacitor in a phase advance or a phase lag direction.